This invention relates generally to structures that may be built using masonry blocks. More particularly, this invention relates to an apparatus for and method of dressing externally viewable surfaces of masonry blocks used to construct mortarless retaining walls.
Retaining walls are widely used in a variety of landscaping applications. Typically, they are used to maximize or create level areas and also to reduce erosion and slumping. They may also be used in a purely decorative manner. In the past, retaining wall construction was labor intensive and often required the skills of trained tradespeople such as masons and carpenters. More recently, retaining wall construction has become significantly simplified with the introduction of self-aligning, modular molded blocks of concrete that may be stacked in vertical or offset courses without the use of mortar or any special skills. These blocks are available in a variety of shapes and sizes and a great many of them even allow a retaining wall to be curved or sinuous, so that it may be constructed circumjacent a tree, or parallel to a meandering pathway, for example.
Initially, these blocks were available in a limited number of sizes, shapes and textures. However, as the aforementioned blocks have become more and more popular, a greater variety of blocks of different styles have become available to the consumer. A particular style of block that is increasing in popularity is the rustic or weathered look. Rustic or weathered look blocks are desirable for several reasons. First, they convey the impression of craftsmanship that is nowadays frequently absent. Second, their time worn appearance conveys a sense of security and stability. And third, they are visually pleasing to an observer. With rustic or weathered blocks, it is possible to form structures that give the impression that they were constructed by artisans of a bygone era. These styles of blocks are particularly useful in restorative or rehabilitation work, or where certain stylistic and structural standards must be maintained.
A variety of approaches have been used to create rustic blocks. The most elementary and straightforward approach is to take a molded block and hand dress or roughen the surface. This approach has several drawbacks that are difficult to overcome. One, it significantly adds to the cost of the product because it is necessary to hire a person (or more likely, a crew of people) to perform this additional task. And, it may also be necessary to train or otherwise educate a person to perform such a task. Two, it increases the time necessary to produce such a product because hand dressing requires additional, time-consuming steps. Whether at the factory or at a job-site, each block must now be moved to a work station where it is hand dressed prior to use.
Since it is prohibitively expensive to hand dress block, alternative approaches to forming rustic blocks have been attempted. One approach has been to provide a patterned mold that is able to simulate a rustic surface. This approach has its drawbacks. One, It takes time and efforts to create and fabricate a mold. Two, the process of molding a block includes additional time consuming steps. Three, the process is limited to the formation of a particular style of block. And while it eliminates the step of hand dressing, a user is more-or-less stuck with the product as it comes from the mold. Any modification thereafter would defeat the purpose of such a block. And four, the molded surface does not have the appearance of hand dressing that is desired by the increasingly discerning and sophisticated customer.
Another approach is to take a molded block and place it in a rotatable container that tumbles it about (preferably, with other blocks or suitable material). This approach is much more cost effective and efficient that that of hand dressing each block. And, as with hand dressed blocks, each block so produced has a distinctive character. This approach, however, has a major drawback. The problem is that as a block is being tumbled, all of the exterior surfaces are being ground down. While this is a desirable result where the externally viewable surface of the block is concerned, it is an undesirable result for the remaining exterior surfaces of the block, particularly at the sides where the ability of adjacent blocks to be positioned flush against each other in a sealing relation may be compromised. Thus, instead of having linear side surfaces in sealing relation between adjacent blocks, there are now jagged side surfaces that form gaps or spaces therebetween. These gaps allow back-fill material to filter therethrough and accumulate in front of the structure. This is often exacerbated by rainfall that mixes with and transports particulate matter through the gaps, which may stain or otherwise leave residue on lower courses blocks that detracts from the overall appearance of the structure.
Another approach is to form them during the manufacturing process. This is most often accomplished by casting two blocks together in a single mold and splitting them apart along a predetermined plane. This creates two blocks, each with a front face that has the appearance of a natural split rock. A drawback with this approach is that blocks produced in this manner, while attractive, do not convey the impression that they were entirely hand worked. At best, they suggest that the blocks were broken away from a parent material and then machine dressed to predetermined dimensions. Thus, they have tight, thin, straight joints and, when assembled together, give the impression of a unitary structure having a textured surface.
Efforts to create a more realistic looking rustic block based on the aforementioned split-face block have taken several approaches. One approach is to hand dress selected portions of a block. This approach is less labor intensive than hand dressing the entire surface of a block as previously mentioned, but it still has the same aforementioned drawbacks—though to a lesser degree. One, it significantly adds to the cost of the product because it is necessary to hire a person (or more likely, a crew of people) to perform this additional task. And, it may also be necessary to train or otherwise educate a person to perform such a task. Two, it increases the time necessary to produce such a product because hand dressing requires additional, time-consuming steps. Whether at the factory or at a job-site, each block must now be moved to a work station where it is hand dressed prior to use.
Yet another approach uses flails to modify the externally viewable surfaces of blocks. Typically, the flails comprise short sections of chain one end of which is affixed about the perimeter of a rotatable element, the other end of which is attached to a steel head. In operation, the steel heads of the flails strike the entire front surface of a block as they are swung about by the rotatable element. While the flails produce acceptable results, there are several drawbacks. One, in order for the flails to operate at maximum efficiency, they must be swung about at a high rotational speed. This presents potentially dangerous condition, for if a flail were to break loose from the rotating element, they could easily injure people within the vicinity. Two, single or multiple links of a chain could break loose. This means that the flails must be inspected periodically to ensure that there are no cracks or damaged links that may lead to failure. The result is down time and loss of production. Three, as the flails strike a surface, they tend to crush or blast away the material away and form large amounts of dust. This presents health concerns such as ingestion, inhalation and sanitation. Moreover, such dust may create dangerous operating conditions by reducing visibility within the immediate vicinity or by settling upon equipment and obscuring essential components such as gauges or warning stickers. And, airborne dust also creates the potential for explosions initiated by sparks or electrical discharges. Four, flails are noisy, and people in the vicinity may be adversely affected by prolonged exposure to the noise associated with operation of such a device—even with the provision of ear protection.
There is a need for a masonry block that, when assembled together with other masonry blocks to form a structure, creates the impression that craftsmen using hand tools constructed the structure. There is also a need for a masonry block that may have marginal areas of its externally viewable surface dressed and still be able to be combined with other masonry blocks to form joints that effectively prevent passage of particulate matter therebetween.
There is also a need for an apparatus that is able to dress externally viewable surfaces of blocks without altering the remaining surfaces of the blocks, and do so in a manner that minimizes the formation of undue amounts of dust. There is yet another need for an apparatus that may be adjusted to accommodate masonry blocks having different dimensions, and which may be configured and arranged to dress only marginal areas of externally viewable surfaces of masonry blocks. There is yet another need for an apparatus that is able to dress a plurality of masonry blocks in an expedient and efficient manner.
And, there is a need for a method by which rustic masonry blocks may be fabricated.